Generally, polyolefin resins are relatively inexpensive, have excellent chemical resistance, water resistance, heat resistance, etc., and are therefore used in a wide variety of applications, such as materials for automotive parts, electrical parts, building materials, food packaging films, etc. However, polyolefin resins with such excellent properties are crystalline and non-polar, and thus coating or bonding these resins are difficult.
To coat or bond such low-adhesion polyolefin resins, chlorinated polyolefins exhibiting strong adhesion to polyolefin resins have been heretofore used as binder resins. For example, an isotactic polypropylene chlorinated to a chlorine content of 20 to 40 wt. % has been proposed as a binder resin for printing inks for polypropylene films (JP 46-27489 B). Further, propylene-ethylene copolymers chlorinated to a chlorine content of 20 to 40 wt. % have been proposed as binder resins for printing inks or adhesives for polyolefins (JP 48-5507 A and JP 48-4534 A).
Furthermore, carboxylic acid- and/or carboxylic anhydride-containing low-chlorinated propylene-α-olefin copolymers with a chlorine content of 5 to 50 wt. % have been proposed as binder resins for primers and coating materials for polyolefin molded articles (JP 59-75958 A and JP 60-99138 A).
However, since such chlorinated polyolefins are usually used in the form of solutions in organic solvents such as toluene, xylene, etc., a large amount of organic solvent is released into the air during coating application, polluting the environment and causing hygiene problems. Moreover, film formation using such solutions requires high-temperature long-time drying, and thus has low production efficiency.